DESCRIPTION: Agricultural pesticide use may be the most significant source of environmental endocrine disruptor exposure in the United States. California, the leading agricultural state in the nation, is the only state that requires reporting of all agricultural pesticide use. The Pesticide Use Reporting (PUR) data indicates that over 600, 000 pounds of ED pesticides are used annually in the Salinas Valley alone. Based on animal and human evidence, prenatal exposure to other endocrine disruptors such as PCBs may result in neurodevelopmental effects and these outcomes may be one of the most sensitive indicators of toxicity. Although animal studies suggest that endocrine disrupting pesticides potentially could affect neurodevelopment, no studies to date have examined these effects in humans. The objectives of this study are: 1) to determine whether in utero exposure to endocrine disrupting (ED) pesticides, such as non-persistent ED pesticides and organochlorine pesticides, is associated with adverse effects on the neurobehavioral development of children; and 2) to identify population correlates of exposure, e.g., occupation, season, PUR data) so that appropriate interventions can be developed in the future to reduce exposure. We propose to examine this relationship in approximately 550 children from predominantly low-income Latino farmworker families living in the Salinas Valley of Monterey County, California. These children, whose mothers were enrolled during pregnancy, are participants of CHAMACOS, a study of the NIH- and EPA-funded Center for Children=s Environmental Health Research, which aims to investigate exposure to organophosphate pesticides and potential health effects in children. We will measure biomarkers of exposure to 14 organochlorine pesticides in archived CHAMACOS serum samples collected at 26 weeks gestational age, and 16 non-persistent ED pesticides or their metabolites in archived maternal urine samples collected at 13 and 26 weeks gestational age. We will investigate the association of these biomarkers with neurodevelopment of newborns (Brazelton) and, 6, 12, and 24 month olds. Mothers are interviewed prenatally and postnatally about their sociodemographic characteristics, habits, housing, exposure, work and medical history. Geographic coordinates of residences are determined in home visits and will be linked to the PUR data. This study will provide the first data on exposure and health effects of ED pesticides in a highly exposed population, complete the exposure profile of CHAMACOS children, and target interventions to reduce child exposures.